Lightning Studies Based on Measurements Spanning the Ranges from Radio Frequency to Optical (including Infrared and Ultraviolet) to Gamma-Rays

基于从射频到光学（包括红外线和紫外线）再到伽马射线的测量的闪电研究

• 批准号: 2114471
• 负责人: Vladimir Rakov
• 金额: $ 100.69万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-15 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2114471&HistoricalAwards=false
• 关键词: Lightning; Studies; Based; Measurements; Spanning

Lightning is a spectacular natural phenomenon but also a severe hazard to human life and property. A number of fundamental questions on how lightning actually works are still open and cannot be answered without the use of nontraditional approaches and tools. Optical observations of lightning in an unprecedentedly wide wavelength range using a unique array of high-speed framing cameras operating, besides the traditional visible-range, also in the medium-to-far infrared (IR) and near ultraviolet (UV) ranges will be performed to get a view of lightning processes that has never been possible before. IR images will provide a measure of temperature in different parts of the lightning channel and UV images will make it possible to detect “cold” lightning processes (such as corona streamer bursts) which play a fundamental role in determining lightning behavior. Observations will be carried out at the Lightning Observatory in Gainesville (LOG), Florida, in conjunction with recordings of corresponding radio-frequency electromagnetic field and penetrating radiation (x-rays and gamma-rays) signatures. The anticipated results will potentially impact an unusually large number of areas/disciplines, including, besides the lightning physics, (1) the global electric circuit, in which corona is one of the key processes that keep the Earth negatively charged, (2) cloud electrification (corona at ground may be a significant contributor to the formation of the lower positive charge region), (3) high-energy atmospheric physics (corona streamer bursts produce x- and gamma-rays), (4) lightning protection (corona-emitting systems sometimes are claimed to control the lightning termination point), and (5) thunderstorm warning (occurrence of corona is an indicator of thunderstorm hazard).The project is aimed at answering the following new science questions: (1) What is the role of corona streamers in the various phenomena associated with thunderstorms and lightning? (2) What can we learn from direct comparison of high-speed recordings of lightning in the IR, visible, and UV ranges? (3) What processes (besides the attachment process) create loops in the lightning channel? (4) How fundamental are the differences between +CGs and –CGs? Observations with the new UV camera will first target the streamer zone of descending leader branches and that of upward unconnected leaders. Then, the possibility of imaging the common streamer zone formed during the lightning attachment process and the lightning channel corona sheath will be explored. IR images will allow clear imaging of the evolution of the early stage of return-stroke process, which is impossible in the visible range due to significant light scattering. Also, IR images will be used to distinguish between parts of the leader channel network that are at different stages of their heating and cooling processes, while UV images will show essentially cold (and generally undetectable in the visible range) streamer formations. Synergistic results will be obtained from simultaneous observations in this unprecedentedly wide optical wavelength range, which will be performed in conjunction with the corresponding recordings of RF electromagnetic field signatures and energetic radiation. Further, the recently observed mysterious loops in the lightning channel will be examined and conditions under which +CGs exhibit features characteristic of –CGs will be identified.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

闪电是一种壮观的自然现象，也是对人类生命财产的严重危害。关于闪电如何工作的一些基本问题仍然是开放的，如果不使用非传统的方法和工具，就无法回答。在前所未有的宽波长范围内，使用独特的高速分幅相机阵列对闪电进行光学观测，除了传统的可见光范围外，还将在中远红外（IR）和近紫外（UV）范围内进行观测，以获得前所未有的闪电过程视图。红外图像将提供闪电通道不同部分的温度测量，紫外线图像将使探测“冷”闪电过程（如日冕流光爆发）成为可能，这在确定闪电行为方面起着基本作用。观测将在佛罗里达州盖恩斯维尔的闪电观测站进行，同时记录相应的射频电磁场和穿透辐射（x射线和伽马射线）特征。预期的结果将潜在地影响异常多的领域/学科，包括，除了闪电物理，(1)全球电路，其中日冕是保持地球负电荷的关键过程之一，(2)云电气化（地面日冕可能是形成较低正电荷区域的重要因素），(3)高能大气物理（日冕流爆发产生x射线和伽马射线），(4)防雷（电晕发射系统有时被称为控制闪电终点），(5)雷暴警报（电晕的发生是雷暴危险的一个指标）。该项目旨在回答以下新的科学问题：(1)在与雷暴和闪电有关的各种现象中，日冕飘带的作用是什么？(2)直接比较闪电在红外线、可见光和紫外线波段的高速记录，我们能学到什么？(3)除附着过程外，哪些过程会在闪电通道中产生环路？(4) + cg和- cg的根本区别是什么？新的紫外相机的观测将首先瞄准向下的导枝和向上不连接的导枝的飘带区。然后，探索闪电附着过程中形成的共流带和闪电通道日冕鞘成像的可能性。红外图像将允许清晰成像的早期阶段的演变回冲程，这是不可能的可见光范围内，由于显著的光散射。此外，红外图像将用于区分处于加热和冷却过程不同阶段的先导通道网络的部分，而紫外图像将显示本质上是冷的（通常在可见范围内无法检测到）流光地层。协同结果将从这一前所未有的宽光学波长范围内的同时观测中获得，这将与射频电磁场特征和能量辐射的相应记录一起进行。此外，我们将研究最近在闪电通道中观测到的神秘环路，并确定+ cg表现出- cg特征的条件。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Unusual Plasma Formations Produced by Positive Streamers Entering the Cloud of Negatively Charged Water Droplets

• DOI: 10.1029/2021jd035821
• 发表时间: 2021-09
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: A. Kostinskiy;N. Bogatov;V. Syssoev;E. Mareev;M. Andreev;M. Bulatov;D. Sukharevsky;V. Rakov

Ground‐Based Observation of a TGF Occurring Between Opposite Polarity Strokes of a Bipolar Cloud‐To‐Ground Lightning Flash

对双极云的相反极性冲程之间发生的 TGF 进行地面观测 — 至 — 地面闪电

• DOI: 10.1029/2021jd036130
• 发表时间: 2022
• 期刊: Journal of Geophysical Research: Atmospheres
• 作者: Kereszy, I.;Rakov, V. A.;Ding, Z.;Dwyer, J. R.
• 通讯作者: Dwyer, J. R.

Transient phenomena in positive cloud-to-ground lightning discharges

• DOI: 10.1038/s42005-022-01087-8
• 发表时间: 2022-12
• 期刊: Communications Physics
• 影响因子: 5.5
• 作者: Z. Ding;V. Rakov;Yanan Zhu;M. D. Tran;I. Kereszy

Energetic Radiation from Subsequent-Stroke Leaders: The Role of Reduced Air Density in Decayed Lightning Channels

后续中风先导的高能辐射：空气密度降低在衰减闪电通道中的作用

• DOI: 10.3390/app12157520
• 发表时间: 2022
• 期刊: Applied Sciences
• 作者: Kereszy, Istvan;Rakov, Vladimir;Czumbil, Levente;Muresan, Alexandru;Ding, Ziqin;Micu, Dan;Cooray, Vernon
• 通讯作者: Cooray, Vernon

Multiple Strokes Along the Same Channel to Ground in Positive Lightning Produced by a Supercell

• DOI: 10.1029/2021gl096714
• 发表时间: 2021-12
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Yanan Zhu;P. Bitzer;V. Rakov;M. Stock;J. Lapierre;E. DiGangi;Z. Ding;Bruno L. Medina;L. Carey